Insulating joint



Oct. 25, 1932.`

J. RAH

INSULATING JOINT Oct. 25, 1932.

J. RAH

INSULA TING JOINT Filed Feb. 8. 1930 2 Sheets-Sheet 2 Patented Oct. 215, L1932 UNITED STATES PATENT OFFICE JOSEPH RAH, OF CHICAGO, ILLINOIS, ASSIGNOR T THE DELTA-STAR ELECTRIC COM- P AN Y, OF CHICAGO, ILLINOIS, A CORPORATION 0F ILLINOIS IN SULATIN Gr JOINT Vpplication led February This invention relates to cable joints, and has particularly to do with a novel and 1mproved type of insulating joint for underground cables, with the object of sectionallzing the exterior sheath of a cable in an 011- tight manner and in `insulated relation. s

It is one of the objects of the present 1nvention to provide an insulating joint for metal sheathed cables which joint is so arranged that it may be applied to any part of a cable, including even a curved or bent portion thereof. p

It is a further object of the present invention to provide an insulating sleeve for a cable joint wherein the mechanical connection between the insulation and the metallic parts is such as to place the insulation primarily under compressive stress as distinguished from bending or tension stresses.

There are other objects and features which will appear as the description progresses.

The invention will now be described in connect-ion with the accompanying two sheets of drawings, in which:

Figure -1 shows the cross section of an oiltightK insulating joint according to one way of carrying the invention out in practice;

Fig. 2 illustrates a sectional view taken on line 2-2 in Figure 1; and v Figure 3 illustrates a modilication of an oil-tight insulating joint having adjustable and mechanically removable means for attaching 'the lead sheath to the insulating casing.

\ yed protuberances 13 Like parts in the drawings are indicated by like reference numerals.

lReferring now to the drawings, Figure 1 and Figure 2, numeral 1 designates a tubular insulating casing for exteriorly embracing a cable. Mechanically attached at both ends of this insulating casing are the clamp members 2 and 3. Each of these clamp members consists, as is shown in Figure 2, of a number of sections 4, '5 and 6, provided with peripheral extensions 7.-8, 9-10, 11-12, respectively, which are assembled peripherally around and embracing the peripheral roundand 14 provided on the insulating casing 1. Interposedbetween the sections 4, 5, 6, of the clamping members and s, 1930. serial No. 426,813.

It will be understood, of course, that the f number of clamp sections shown and disclosed above in connection with the manner of reducing the invention to practice as illusersv trated'in Figures 1 and 2, is more or less arbitrary and intended to serve primarily the purpose of description and explanation. There may be more or less clamp sections provided, or these sections may be attached in a manner differing in detail from the manner illustrated, without altering the inventive idea of using sectional clamps mechanically attached to the insulating casing.

The advantages resulting from the use of such sectional clamps are obvious. The insulating casing is securely embraced by forces acting from .a plurality of circumferentially symmetrical points, holding the insulating casing tight and without any danger of breakage. Prior constructions have disclosed a type of clamp permanently attached to an insulating casing by cementing or by moulding the metal fittings into the insulating material or the like.

The superiority of the instant case in which mechanically removable and adjustable sectional clamping means are used, over rigidly attached mounting chambers, as intimated above, will be readily appreciatedf In case of the latter, strains and stresses imposed upon the structure will not be equalized at all, but will react upon the unit, and under f;

certain conditions react to the detriment of the assembly. In the present structure, due to the sections of the clamps gripping the insulating body firmly from a plurality of peripherally symmetrical points, and due to i with a section of l lation thereto. It is,

the cushion effect of the layer interposed bestrains and stresses. will be equalized and the -assembly will adjust itself automatically t o stresses imposed upon the same under ordinary conditions.

Continuin now the description of the invention, a wiping sleeve, such as and 31 is attached to the clamp members 2 and 3, at both ends of the insulatingA casing 1, by means of cap screws 32-33, and 34e-35, respectively, which are inserted into the corresponding threaded holes, such as 26, 27, 28 and 29, von the clamp members as shown in Figure 2. It is understood, of course, that there are four such cap screws for holding each of the wiping sleeves in engagement with the corresponding clamp sections. Gaskets 36 and 37 are interposed between the corresponding ends of the insulating casing 1 and the flanges of the corresponding wiping sleeve attached to it.

The cable is drawn through the. assembly,

its exterior lead sheath removed and the ends 38 and 39, respectively, of the wiping sleeve 30 and 312 are, in case of wiping sleeves having lead skirts, attached to the lead sheath of the cable at both sides of the assembly, by means of hammering, rolling, or pressing, in the usual manner, joining the ends of corresponding wiping sleeve in oil-tight reof course, understood that rigid castwiping sleeves may be employed in place of leeves havinglead skirts.

No hammering, rlling or pressing will be necessary in such a case. The sleeve is sim- P ply attachedexteriorly to the sheath, and a lead ring or sleeve is applied to the junction for sealing the same. A

The oil-tight insulating joint, sectionalizing the lead sheath of the cable is now completely assembled and joined to the sheath of the cable in oil-tight relation. It will be appreciated that the construction as described, is of utmost simplicity in design and operation and at the same time reliable in use, having numerous novel features not found in prior devices of this kind.

A modification of the device just described, 4in which mechanically removable and adjustable means for securing the lead sheath of the cable in oil-tight relation to the two ends of the insulating body are provided in place of the wiping sleeve, is shown in Figure 3.

A cursory inspection of the drawing shown in Figure 3 will show that the same split, or sectional, clamp members are attached mechanically to the insulating casing as were described in connection with Figures 1 and 2. Accordingly, a detailed description of these clamping members will be omitted in the following explanations.4 Details in Figure 3 which correspond to Figures 1 and 2 aredesignated with like reference numerthe lead sheath to the' als, and the v-description of Figures l and 2- may be consulted for supplying information omitted here for the sake of avoiding unnecessary repetition of matter.

Referring now to Figure 3, the cable, entering the' insulating joint at 4() and leaving the same at is again stripped of its external lead sheath, and the ends 41 and 64 ofthe sheath are mechanically and adjustably joined to the insulating body 1 and in oil-tight relation thereto.

This is accomplished by means of attaching to each end of the insulating body 1 a sleeve member 44 and 56, respectively, having flanges 45 and 51 for attachment to the clamping members 2 and 3, by interposing gaskets 36 and 37, as was explained in connection with the wiping sleeves 30 and 31 in the structure described previously by referring to Figures 1 and 2. These sleeve members 44 and 56 are alike in structure and function, and only one will be fully explained for convenience of description, that is, the one attached atvthe lower end of the insulating body 1 and designated by numeral 44.

I The lower circular portion 43 of this mechanical sleeve member is widened and provided with an internal thread 47 and with a circular interiorly projecting rim 57. u The end 41 of the cable sheath is inserted into this rim portion, and securely fastened to it by means of the circularnut member 46 provided with a thread to engage the threaded part 47 of the sleeve extension 43. The end 48 of the nut member 46 is rounded and conforms to the shape of therim 57 to rovide a secure grip and tight fit for the end of the cable sheath 41. i

^ The other end 64 of the lead sheath is secured in exactly the same manner, by means of the nut member 63, fastening the same ibs tothe rim 58 of the sleeve 56, which in turn is fastened to thecorresponding end of the insulating casing provided with holes 52 and 53 for taking the cap screws 32 and 33.

Itis believed that the above descriptionV of 1 by means of flange 51 the modification shown in Figure 3 will sufice for fully disclosing the inventive features; and, in summing up the functions and advantages of the device over devices disclosedprior to my invention, it maybe said` and will be appreciated, that Ihave provided a novel, oil-tight insulating joint for sectionalizing the external sheath off underground cable for the purpose of reducing induction and thereby reducing power loss, incorporating numerous novel structural and functional features which represent an advance in the art in many respects.'

Accordingly, I desire to secure Letters Patent for my invention which is particularly defined in the following claims:

I claim:

1. A device for interrupting the conductive continuity of the exterior shea'thof an underground cable while maintaining the continuity of the cable insulator and of the cable conductors, comprising a unitary tubular insulating casing for receivingk said cable, an enlargement near each end of said casing and integral therewith, sectional clamping means,.int'ernal grooves in .said clamping means for embracing said enlargements on said casing, packing means in said grooves for cushioning said clamping means on said enlargements, a gasket positioned at each end of said casing, tubular sleeve means engaging each of said gaskets at each end of said casing, the inner diameter of said sleeve means corresponding substantially to the inner diameter of said casing, means for removably attaching said sleeve means to said clamping| means, a laterally extending enlargement on each of said sleeve means, an annular groove in said ylaterally extending enlargement for receiving the sheath. of said cable at the end of each sleeve means, an internal thread in said radially extending enlargement on each sleeve, and a tubular screw for fastening the sheath of said cable to the enlargement on each sleeve and in oil-tight relation therewith, said tubular screw having a rounded head portion for clamping saidsheath in the annular groove in said enlargement on the sleeve and a cylindrical portion at the end thereof for engaging the outer diameter of said sheath, said cylindrical portion and said rounded head portion of lsaid tubular screw being separated by an internal annular notch in said screw.

2. A device for interrupting the electrical continuity of a metallic sheath of a continuous run of cable, said device comprising a tubular insulator adapted to be slipped over a cable and of an internal diameter greater than the external diameter of a cable over which it is to be slipped, whereby the insulator may be slid over bends in the cable, and a pair of sleeve meansconnected to the opposite ends of the insulator and adapted to constitute a portion of a mechanical luidtight connection between each end of the insulator andtheadjacent sheath, portion of a cable, the connection between each of the sleeve means andthe tubular insulator including a flanged split clamp to which the sleeve is connected and a ball and socket joint between the insulator and each of the split clamps to permit a slight angular adjusting motion of each of the sleeve means with respect to the insulator, whereby the device `may be located along a curved portion of a cable while maintaining each of the sleeves directed substantially axially of the adjacent cable portion.

`3. A device for interruptingthe electrical continuity of a metallic sheath of' a continuous run of cable, tubular insulator adaptedto be slipped over said device comprising a a cable and of an internal diameter greater than the external diameter of a cable over which it is to be slipped, whereby the insulator may be slid over bendsV in the cable, and a pair of sleeve means connected to the opposite ends of the insulator and adapted toconstitute a portion of a mechanical fluidtight connection between each end of the insulator and the adjacent sheath portion of a cable, the connection between each of the sleeve means and the tubular insulator in- `adjacent cable portion, each of the ball and socket joints including an outwardly projecting peripheral bead integral with the insulator and wedged into a mating depression in the split clamp as the clamp is clamped to the insulator, whereby the clamping force is one of compression on the bead and tension on the clamp.

4. A device for interrupting the electrical continuity of a metallic sheath of a continuous run of cable, said device comprising a tubular insulator adapted to be slipped over a cable and of an internal diameter greater than the external diameter of a cable over which it is to be slipped, whereby the insulator may be slid over bends in the cable, and a pair of sleeve means connected to the opposite ends of the insulator and adapted to constitute a portion of a mechanical fluidtight connection between each end of the insulator and the adjacent ysheath portion of a cable, the connection between each of the sleeve means and the tubular insulator including a flanged split clamp to which the sleeve is connected and a ball and socket joint between the insulator and each of the split clamps to permit a slight angular adjusting motion of each of the sleeve means with respect to the insulator, whereby the device may be located along a curved portion of a cable while maintaining each of the sleeves directed substantially axially of the adjacent cable portion, the outerend of each sleeve including a shoulder against which the end of the, sheath bears, and a clamping member removably secured to the end of each sleeve and clamping the end of the sheath to said shoulder to form a liquidlargement, an internal thread in said enlargement, a tubular screw for engaging said thread, the head of Said tubular screw being annularly rounded to clamp said cable sheath against said annular groove, the other end of said tubular screw being cylindrical for engaging the outerdiameter of said cable, and an intermediate annular notch internally of said tubular screw .between said cylindrical portion and said annularly rounded head portion thereof.

t3. A device of the class described, for sectionally interrupting the conduotivecontinuity of the external sheath of a cable, comprising a unitary tubular insulating casing, the inside of said casing being substantially cylindrical, circular enlargements on said casing and integral therewith,.one disposed near eachend of said casing, a sectional clamp removably secured to each of said circular enlargements, a gasket positioned at each end of said casing, a tubular sleeve of said casing, said sleeve-having a laterally extending ange and an laxially extending tubular portion, said flange of said sleeve being positioned in engagement with said gasket at the end of said casing to provide an oil tight joint between said sleeve and said casing, screw means axially extending through said flange on each sleeve and engaging threaded holes in said clamping means secured to said casing for securing said sleeve lin position, part of the axially extending sleeve portion being cylindrical and its inner diameter corresponding substantiallyto the inner diameter of said casing, sleeve being of substantially L-shaped cross section with an annular groove at the base thereof for receiving the end of said cable sheath, and a tubular screw cooperating with said sleeve for clamping said sheath in engagement with said annularH groove in said sleeve.

7. A device of the class described, for sectionally interrupting the conductive continuity of the external sheath of a cable, comprising a unitary tubularinsulating casing, the inside of said casing being substantially cylindricahcircular enlargements on said casing and integral therewith, one disposed near each end of said casing, a sectional clamp removably and yieldably secured to each of said circular enlargements, a gasket positioned at each end of said casing, atubular sleeve for each end of said casing, said sleeve having a laterally .extending flange and an said flange axially extending tubular portion` oi said said sleeve being positioned in engagenient with said gasket at the end of said casf or each end l cross section with an annular groove at the base thereof for receiving the end of said cable sheath, and a tubular screw cooperating with said sleeve for clamping said sheath in engagement with said annular groove in said sleeve, said tubular screw having an annularly rounded head portion for engaging said sheath and for clamping said sheath against saidannular roove and a substantially cylindrical gui e portion for circumerentially engaging the ree sheath of said cable, and an annular intermediate internal groove'between said head portion and said guide portion.

In witness whereof, l hereunto subscribe my name this 5th day of February, 1930.

JOSEPH RAH.

the end of said ing to provide an oil tight joint between said sleeve and said casing, extending through said ange on each sleeve and engaging threaded holes in said clamping .means secured to said casing for securing said sleeve in position, part screw means axially of the axially extend- 

